1. Field of the Invention
Ths invention relates to a T-square type measuring device for locating and marking score lines along the length of a duct board such that the score lines can be formed at preselected locations on the interior surface of the duct board for folding thereof about itself and about the score lines into a multi-sided configuration which defines a hollow interior duct or conduit.
2. Description of the Prior Art
Measuring instruments and devices incorporating a T-square construction have been known in the prior art for many years. Typically, such devices were construction and utilized for the purposes of establishing a true straight edge or a reference line or base disposed in perpendicular relation to a central transverse or longitudinal axis of a paper or object to which the T-square construction was applied.
In the drafting technology, such devices were used as a true level horizontal base for the purpose of drawing other preferred angularly oriented lines. However, the T-square construction has been developed and expanded into numerous other technologies as evidenced by the devices disclosed in U.S. Pat. Nos. to Barrier, 685,369; Blizard, et al, 1,053,083; and Marsella, et al, 2,058,091. As disclosed in the above-noted patents, the T-square construction is used in combination with a scale, for purposes of measurement, and also with other diverse types of tools such as a cutting tool as disclosed in the above-noted patent to Marsella et al.
Other existing U.S. patents including U.S. Pat. No. 4,403,423 to Ford shows a drafting instrument including what may be referred to broadly as a T-square construction incorporating a reference scale. Also the patent to Wing, U.S. Pat. No. 4,279,081 discloses a wall board T-square specifically structured to have connecting elements secured thereto for the temporary attachment of the T-square to the face of a product such as a gypsum wall board so that a board cutting knife may be applied to the surface or face of the wall board. A cutting knife is thereby guided along a predetermined cut and prevents inadvertant damage or arbitrary cutting of the face of the board at any other location.
In the formation of ducting used for air conditioning, duct board normally is manufactured in sheets. These sheets are individually measured and scored so as to be folded upon themselves into a conduit or duct configuration having a hollow interior and a multi-sided exterior. Normally, when a large number of such duct boards are to be scored, such is done by conventional machinery known in the industry. However, such machinery is expensive and relatively heavy and bulky an does not lend itself to be used in the field. Therefore, there is a need in the industry for a measuring device capable of dimensioning and marking score lines of a duct board for cutting thereof. Such a measuring device is particularly applicable for field use wherein at least one and preferably a plurality of sheets need be properly dimensioned and scored and the larger, heavier machinery utilized for such purposes is not available.